A high frequency device that includes an antenna is used for various purposes such as radar or communication. For example, PTL 1 discloses a microwave moving body detecting device.
FIG. 9 is a block diagram illustrating a schematic configuration of a microwave moving body detecting device 201 of PTL 1.
The microwave moving body detecting device 201 includes a high frequency circuit board 202 having a transmit antenna 203a, a receive antenna 203b, and a high frequency circuit unit 211 and a low frequency circuit board 210 having a signal processing circuit unit 208, and has an operation frequency of 10 GHz.
A microwave oscillated by a microwave oscillator 205 is emitted into a space from the transmit antenna 203 via a directional coupler 204. The microwave reflected by a moving body in the space is received by the receive antenna 203b. The received microwave passes through the directional coupler 204 and is superposed, in a mixer 206, on the microwave oscillated by the microwave oscillator 205 to be a Doppler signal which is proportional to a speed of the moving body. The Doppler signal passes through a low-pass filter 207 and is input to a signal processing unit 208. The signal processing circuit unit 208 selectively amplifies a frequency component which is generated by movement of a person, detects a motion of the person on the basis of amplitude, a duration time, or the like, and outputs a detection signal from a signal line connector 209.